I think that I may have figured out something that could be causing my trackback problem. When testing my own trackbacks to a separate site, I had accidentally marked my own trackback as spam. Since then, my trackback has always been marked as spam on that site, so I use a plugin to see it again.
When a comment is marked as spam, is that information sent to WordPress.org? Because I'm wondering if I accidentally added my personal site to a global spam list.
What makes me think this is that any trackback from djosephdesign.com/blog gets marked as spam on my second blog, and the trackbacks don't even appear in other blogs (like Test Track).
I used CJD Spam Nuke on my other blog to discover my comments were "spam." Can someone else help me determine if my blogs are global spam?